A Mechanistic Understanding of Neuronal Activity Promotion of High-Grade Glioma Growth through Activity-Regulated Secretion of Neuroligin-3

 描述(由申请人提供)：胶质瘤细胞行为的微环境决定因素尚不完全清楚。胶质瘤发生的年龄和神经解剖位置偏好表明起源细胞与其微环境之间存在重要的相互作用，并提示神经发育和/或可塑性机制的失调。我们最近发现，活跃的神经元对正常神经前体细胞和少突胶质前体细胞有丝分裂作用，这两种细胞可能是高级别胶质瘤的细胞来源。 (HGG)。我们现在初步证明，在儿童胶质母细胞瘤原位异种移植模型中，通过光遗传控制皮质神经元的活动，活跃的神经元在体内类似地促进HGG的增殖。分泌活性调节的丝裂原(S)，作为光遗传刺激的皮质切片的条件培养液，促进儿童和成人患者来源的HGG培养的增殖。突触蛋白神经连接蛋白-3(NLGN3)被认为是主要的有丝分裂原；可溶性NLGN3是促进HGG细胞强劲增殖的充分和必要的因素。NLGN3在胶质瘤细胞中诱导PI3K通路活性和NLGN3的前馈表达，为其作为有丝分裂原的惊人作用提供了机制上的洞察。人HGG中NLGN3的表达水平与患者总生存期呈负相关。这些发现表明活跃的神经元在脑肿瘤微环境中的重要作用，并确认分泌的神经连接蛋白-3是一种意想不到的促进神经元活性调节的肿瘤生长的机制。这项拟议的工作旨在进一步研究NLNG3与高级别胶质瘤细胞之间的直接相互作用。我们将在活体光遗传模型中直接探讨NLGN3在神经活动调节胶质瘤生长中的必要性。此外，这项研究将确定分泌、受体结合和下游信号通路的机制。这项拟议的工作突出了以前被低估的神经元活动在胶质瘤微环境中的重要性，将导致对新发现的胶质瘤有丝分裂原NLGN3的更好的机制理解，并可能发现新的治疗靶点，以更好地治疗这些致命的脑肿瘤。

 DESCRIPTION (provided by applicant): Microenvironmental determinants of glioma cell behavior are incompletely understood. The age and neuroanatomical location predilections of glioma occurrence indicate important interactions between the cell of origin and its microenvironment and suggest dysregulation of mechanisms of neurodevelopment and/or plasticity. We recently showed active neurons exert a mitogenic effect on normal neural precursor and oligodendroglial precursor cells, the putative cellular origins for high-grade glioma (HGG). We now preliminarily demonstrate that active neurons similarly promote HGG proliferation in vivo using optogenetic control of cortical neuronal activity in a patient-derived pediatric glioblastoma orthotopic xenograft model. Activity-regulated mitogen(s) are secreted, as the conditioned medium from optogenetically stimulated cortical slices promoted proliferation of pediatric and adult patient-derived HGG cultures. The synaptic protein neuroligin-3 (NLGN3) was identified as the leading candidate mitogen; soluble NLGN3 was sufficient and necessary to promote robust HGG cell proliferation. NLGN3 induced PI3K pathway activity and feed-forward expression of NLGN3 in glioma cells, providing mechanistic insight into its surprising role as a mitogen. NLGN3 expression levels in human HGG negatively correlated with patient overall survival. These findings indicate the important role of active neurons in the brain tumor microenvironment and identify secreted neuroligin-3 as an unexpected mechanism promoting neuronal activity-regulated cancer growth. The proposed work aims to investigate further the direct interaction between NLNG3 and high-grade glioma cells. We will directly probe the necessity of NLGN3 in neuronal activity regulated glioma growth in an in vivo optogenetic model. Further, the research will identify mechanisms of secretion, receptor binding, and downstream signaling pathways. The proposed work highlights the previously under-recognized importance of neuronal activity in the glioma microenvironment, will result in a better mechanistic understanding of the newly identified glioma mitogen NLGN3, and may identify novel therapeutic targets to better treat these deadly brain tumors.